The appearance of the crossbow as a serious military implement along the northern rim of the western Mediterranean at about the middle of the 9th century marked a growing divergence between the technology of war in Europe and that of the rest of the world. It was the first of a series of technological and tactical developments that culminated in the rise of infantry elites to a position of tactical dominance. This infantry revolution began when the crossbow spread northward into areas that were peripheral to the economic, cultural, and political core of feudal Europe and where the topography was unfavourable for mounted shock action and the land too poor to support an armoured elite. Within this closed military topography, the crossbow soon proved itself the missileweapon par excellence of positional and guerrilla warfare.

Escorial, El; crossbowSection of a mural showing a man using a crossbow; in the Hall of Battles, El Escorial, near Madrid.Ken Welsh/age fotostock

The reasons for the crossbow’s success were simple: crossbows were capable of killing the most powerful of mounted warriors, yet they were far cheaper than war-horses and armour and were much easier to master than the skills of equestrian combat. Also, it was far easier to learn to fire a crossbow than a long bow of equivalent power. Serious war bows had significant advantages over the crossbow in range, accuracy, and maximum rate of fire, but crossbowmen could be recruited and trained quickly as adults, while a lifetime of constant practice was required to master the Turkish or Mongol composite bow or the English longbow.

The crossbow directly challenged the mounted elite’s dominance of the means of armed violence—a point that the lay and ecclesiastical authorities did not miss. In 1139 the second Lateran Council banned the crossbow under penalty of anathema as a weapon “hateful to God and unfit for Christians,” and Emperor Conrad III of Germany (reigned 1138–52) forbade its use in his realms. But the crossbow proved useful in the Crusades against the infidel and, once introduced, could not be eradicated in any event. This produced a grudging acceptance among the European mounted elites, and the crossbow underwent a continuous process of technical development toward greater power that ended only in the 16th century, with the replacement of the crossbow by the harquebus and musket.

An independent, reinforcing, and almost simultaneous development was the appearance of the English longbow as the premier missile weapon of western Europe. The signal victory of an outnumbered English army of longbowmen and dismounted men-at-arms over mounted French chivalry supported by mercenary Genoese crossbowmen at Crécy on August 26, 1346, marked the end of massed cavalry charges by European knights for a century and a half.

Another important and enduring discovery was made by the Swiss. At the Battle of Morgarten in 1315, SwissEidgenossen, or “oath brothers,” learned that an unarmoured man with a 7-foot (200-cm) halberd could dispatch an armoured man-at-arms. Displaying striking adaptability, they replaced some of their halberds with the pike, an 18-foot spear with a small piercing head. No longer outreached by the knight’s lance, and displaying far greater cohesion than any knightly army, the Swiss soon showed that they could defeat armoured men-at-arms, mounted or dismounted, given anything like even numbers. With the creation of the pike square tactical formation, the Swiss provided the model for the modern infantry regiment.

halberd; pikeHalberd and pike in battle near Ins, Berne canton, in 1375. Encumbered by heavy armour, the mounted French and English mercenaries are cut down by disciplined Swiss infantrymen wielding long armour-piercing weapons. From the Amtliche Chronik by Diebold Schilling, 15th century; in the Burgerbibliothek Bern (MSS. hist. helv. 1.1, fol. 205). Burgerbibliothek Bern

The idea of mounting a bow permanently at right angles across a stock that was fitted with a trough for the arrow, or bolt, and a mechanical trigger to hold the drawn string and release it at will was very old. Crossbows were buried in Chinese graves in the 5th century bce, and the crossbow was a major factor in Chinese warfare by the 2nd century bce at the latest. The Greeks used the crossbow principle in the gastrophetes, and the Romans knew the crossbow proper as the manuballista, though they did not use it extensively. The European crossbow of the Middle Ages differed from all of these in its combination of power and portability.

Stirrup crossbow, French, 14th centuryCourtesy of the West Point Museum Collections, United States Military Academy

In Europe, crossbows were progressively developed to penetrate armour of increasing thicknesses. In China, on the other hand, crossbow development emphasized rapidity of fire rather than power; by the 16th century, Chinese artisans were making sophisticated lever-actuated rapid-fire crossbows that carried up to 10 bolts in a self-contained magazine. These, however, were feeble weapons by contemporary European standards and had relatively little penetrating power.

Mechanical cocking aids freed the crossbow from the limitations of simple muscular strength. If the bow could be held in a drawn state by a mechanical trigger, then the bow could be drawn in progressive stages using levers, cranks, and gears or windlass-and-pulley mechanisms, thereby multiplying the user’s strength. The power of such a weapon, unlike that of the bow, was thus not limited by the constraints of a single muscular spasm.

The crossbowman, unlike the archer, did not have to be particularly strong or vigorous, and his volume of fire was not as limited by fatigue. Nevertheless, the crossbow had serious tactical deficiencies. First, ordinary crossbows for field operations (as opposed to heavy siege crossbows) were outranged by the bow. This was because crossbow bolts were short and heavy, with a flat base to absorb the initial impact of the string. The flat base and relatively crude leather fins (crossbow bolts were produced in volume and were not as carefully finished as arrows) were aerodynamically inefficient, so that velocity fell off more quickly than that of an arrow. These factors, combined with the inherent lack of precision in the trigger and release mechanism, made the ordinary military crossbow considerably shorter-ranged and less accurate than a serious military bow in the hands of a skilled archer. Also, the advantage of the crossbow’s greater power was offset by its elaborate winding mechanisms, which took more time to use. The combination of short range, inaccuracy, and slow rate of fire meant that crossbowmen in the open field were extremely vulnerable to cavalry.

The earliest crossbows had a simple bow of wood alone. However, such bows were not powerful enough for serious military use, and by the 11th century they gave way to composite bows of wood, horn, and sinew. The strength of crossbows increased as knightly armour became more effective, and, by the 13th century, bows were being made of mild steel. (The temper and composition of steel used for crossbows had to be precisely controlled, and the expression “crossbow steel” became an accepted term designating steel of the highest quality.) Because composite and steel crossbows were too powerful to be cocked by the strength of the arms alone, a number of mechanical cocking aids were developed. The first such aid of military significance was a hook suspended from the belt: the crossbowman could step down into a stirrup set in the front of the bow’s stock, loop the bowstring over the hook, and by straightening up use the powerful muscles of his back and leg to cock the weapon. The belt hook was inadequate for cocking the steel crossbows required to penetrate plate armour, and by the 14th century military crossbows were being fitted with removable windlasses and rack-and-pinion winding mechanisms called cranequins. Though slow, these devices effectively freed the crossbow from limitations on its strength: draw forces well in excess of 1,000 pounds became common, particularly for large siege crossbows.

The longbow evolved during the 12th century in response to the demands of siege and guerrilla operations in the Welsh Marches, a topographically close and economically marginal area that was in many ways similar to the regions in which the crossbow had evolved three centuries earlier. It became the most effective individual missile weapon of western Europe until well into the age of gunpowder and was the only foot bow since classical times to equal the composite recurved bow in tactical effectiveness and power.

Longbow and arrows, English, 14th century (reproduction)Courtesy of the West Point Museum Collections, United States Military Academy

While it was heavily dependent on the strength and competence of its user, the longbow in capable hands was far superior to the ordinary military crossbow in range, rate of fire, and accuracy. Made from a carefully cut and shaped stave of yew or elm, it varied in length, according to the height of the user, from about five to seven feet. The longbow had a shorter maximum range than the short, stiff composite Turkish or Mongol saddle bows of equivalent draw force, but it could drive a heavy arrow through armour with equal efficiency at medium ranges of 150–300 yards. Each archer would have carried a few selected light arrows for shooting at extreme ranges and could probably have reached 500 yards with these.

The longbow’s weakness was that of every serious military bow: the immense amounts of time and energy needed to master it. Confirmation of the extreme demands placed on the archer was found in the skeletal remains of a bowman who went down with the English ship Mary Rose, sunk in Portsmouth Harbour in 1545. The archer (identified as such by a quiver, its leather strap still circling his spine) exhibited skeletal deformations caused by the stresses of archery: the bones of his left forearm showed compression thickening, his upper backbone was twisted radially, and the tips of the first three fingers of his right hand were markedly thickened, plainly the results of a lifetime of drawing a bow of great strength. The longbow was dependent upon the lifestyle of the English yeomanry, and, as that lifestyle changed to make archery less remunerative and time for its practice less available, the quality of English archery declined. By the last quarter of the 16th century there were few longbowmen available, and the skill and strength of those who responded to muster was on the whole well below the standards of two centuries earlier. An extended debate in the 1580s between advocates of the longbow and proponents of gunpowder weapons hinged mainly on the small numbers and limited skills of available archers, not around any inherent technical deficiency in the weapon itself.

Halberd and pike

The halberd was the only significant medieval shock weapon without classical antecedents. In its basic form, it consisted of a six-foot shaft of ash or another hardwood, mounted by an ax blade that had a forward point for thrusting and a thin projection on the back for piercing armour or pulling a horseman off balance. The halberd was a specialized weapon for fighting armoured men-at-arms and penetrating knightly armour. With the point of this weapon, a halberdier could fend off a mounted lancer’s thrusts and, swinging the cutting edge with the full power of his arms and body, could cleave armour, flesh, and bone. The halberd’s power was counterbalanced by the vulnerability of taking a full swing with both arms; once committed, the halberdier was totally dependent upon his comrades for protection. This gave halberd fighting a ferocious all-or-nothing quality and placed a premium on cohesion.

While the halberd could penetrate the best plate armour, allowing infantrymen to inflict heavy casualties on their mounted opponents, the lance’s advantage in length meant that men-at-arms could inflict heavy casualties in return. The solution was the pike, a staff, usually of ash, that was twice the length of the halberd and had a small piercing head about 10 inches (25 cm) long. Sound infantry armed with the pike could fend off cavalry with ease, even when outnumbered. As with the halberd, effectiveness of shock action with the pike was heavily dependent upon the cohesion and solidity of the troops wielding it. The pike remained a major factor in European warfare until, late in the 17th century, the bayonet gave missile-armed infantry the ability to repel charging cavalry.

Few inventions have had an impact on human affairs as dramatic and decisive as that of gunpowder. The development of a means of harnessing the energy released by a chemical reaction in order to drive a projectile against a target marked a watershed in the harnessing of energy to human needs. Before gunpowder, weapons were designed around the limits of their users’ muscular strength; after gunpowder, they were designed more in response to tactical demand.

Powder horn and gunpowder.Encyclopædia Britannica, Inc.

Technologically, gunpowder bridged the gap between the medieval and modern eras. By the end of the 19th century, when black powder was supplanted by nitrocellulose-based propellants, steam power had become a mature technology, the scientific revolution was in full swing, and the age of electronics and the internal combustion engine was at hand. The connection between gunpowder and steam power is instructive. Steam power as a practical reality depended on the ability to machine iron cylinders precisely and repetitively to predetermined internal dimensions; the methods for doing this were derived from cannon-boring techniques.

Gunpowder bridged the gap between the old and the new intellectually as well as technologically. Black powder was a product of the alchemist’s art, and although alchemy presaged science in believing that physical reality was determined by an unvarying set of natural laws, the alchemist’s experimental method was hardly scientific. Gunpowder was a simple mixture combined according to empirical recipes developed without benefit of theoretical knowledge of the underlying processes. The development of gunpowder weapons, however, was the first significant success in rationally and systematically exploiting an energy source whose power could not be perceived directly with the ordinary senses. As such, early gunpowder technology was an important precursor of modern science.

Early gunpowder

Chinese alchemists discovered the recipe for what became known as black powder in the 9th century ce: this was a mixture of finely ground potassium nitrate (also called saltpetre), charcoal, and sulfur in approximate proportions of 75:15:10 by weight. The resultant powder behaved differently from anything previously known. It burned rapidly on contact with open flame or a red-hot wire, producing a bright flash and dense white smoke. It also produced considerable quantities of superheated gas, which, if confined in a partially enclosed container, could drive a projectile out of the open end. The Chinese used the substance in rockets, in pyrotechnic projectors much like Roman candles, in crude cannon, and, according to some sources, in bombs thrown by mechanical artillery. This transpired long before gunpowder was known in the West, but development in China stagnated. The development of black powder as a tactically significant weapon was left to the Europeans, who probably acquired it from the Mongols in the 13th century (though diffusion through the Arab Muslim world is also a possibility).

Chemistry and internal ballistics

Black powder differed from modern propellants and explosives in a number of important particulars. First, only some 44 percent by weight of a properly burned charge of black powder was converted into propellant gases, the balance being solid residues. The high molecular weights of these residues limited the muzzle velocities of black-powder ordnance to about 2,000 feet (600 metres) per second. Second, unlike modern nitrocellulose-based propellants, the burning rate of black powder did not vary significantly with pressure or temperature. This occurred because the reaction in an exploding charge of black powder was transmitted from grain to grain at a rate some 150 times greater than the rate at which the individual grains were consumed and because black powder burned in a complex series of parallel and mutually dependent exothermal (heat-producing) and endothermal (heat-absorbing) reactions that balanced each other out. The result was an essentially constant burning rate that differed only with the grain size of the powder; the larger the grains, the less surface area exposed to combustion and the slower the rate at which propellant gases were produced.

Nineteenth-century experiments revealed sharp differences in the amount of gas produced by charcoal burned from different kinds of wood. For example, dogwood charcoal decomposed with potassium nitrate was found to yield nearly 25 percent more gas per unit weight than fir, chestnut, or hazel charcoal and some 17 percent more than willow charcoal. These scientific observations confirmed the insistence of early—and thoroughly unscientific—texts that charcoal from different kinds of wood was suited to different applications. Willow charcoal, for example, was preferred for cannon powder and dogwood charcoal for small arms—a preference substantiated by 19th-century tests.

Serpentine powder

The earliest gunpowder was made by grinding the ingredients separately and mixing them together dry. This was known as serpentine. The behaviour of serpentine was highly variable, depending on a number of factors that were difficult to predict and control. If packed too tightly and not confined, a charge of serpentine might fizzle; conversely, it might develop internal cracks and detonate. When subjected to vibration, as when being transported by wagon, the components of serpentine separated into layers according to relative density, the sulfur settling to the bottom and the charcoal rising to the top. Remixing at the battery was necessary to maintain the proper proportions—an inconvenient and hazardous procedure producing clouds of noxious and potentially explosive dust.

Corned powder

Shortly after 1400, smiths learned to combine the ingredients of gunpowder in water and grind them together as a slurry. This was a significant improvement in several respects. Wet incorporation was more complete and uniform than dry mixing, the process “froze” the components permanently into a stable grain matrix so that separation was no longer a problem, and wet slurry could be ground in large quantities by water-driven mills with little danger of explosion. The use of waterpower also sharply reduced cost.

After grinding, the slurry was dried in a sheet or cake. It was then processed in stamping mills, which typically used hydraulically tripped wooden hammers to break the sheet into grains. After being tumbled to wear the sharp edges off the grains and impart a glaze to their surface, they were sieved. The grain size varied from coarse—about the size of grains of wheat or corn (hence the name corned powder)—to extremely fine. Powder too fine to be used was reincorporated into the slurry for reprocessing. Corned powder burned more uniformly and rapidly than serpentine; the result was a stronger powder that rendered many older guns dangerous.

Late medieval and early modern gunners preferred large-grained powder for cannon, medium-grained powder for shoulder arms, and fine-grained powder for pistols and priming—and they were correct in their preferences. In cannon the slower burning rate of large-grained powder allowed a relatively massive, slowly accelerating projectile to begin moving as the pressure built gradually, reducing peak pressure and putting less stress on the gun. The fast burning rate of fine-grained powders, on the other hand, permitted internal pressure to peak before the light, rapidly accelerating projectile of a small arm had exited the muzzle.

Then, beginning in the late 18th century, the application of science to ballistics began to produce practical results. The ballistic pendulum, invented by the English mathematician Benjamin Robins, provided a means of measuring muzzle velocity and, hence, of accurately gauging the effective power of a given quantity of powder. A projectile was fired horizontally into the pendulum’s bob (block of wood), which absorbed the projectile’s momentum and converted it into upward movement. Momentum is the product of mass and velocity, and the law of conservation of momentum dictates that the total momentum of a system is conserved, or remains constant. Thus the projectile’s velocity, v, may be determined from the equation mv = (m + M)V, which gives

where m is the mass of the projectile, M is the mass of the bob, and V is the velocity of the bob and embedded projectile after impact.

The initial impact of science on internal ballistics was to show that traditional powder charges for cannon were much larger than necessary. Refinements in the manufacture of gunpowder followed. About 1800 the British introduced cylinder-burned charcoal—that is, charcoal burned in enclosed vessels rather than in pits. With this method, wood was converted to charcoal at a uniform and precisely controlled temperature. The result was greater uniformity and, since fewer of the volatile trace elements were burned off, more powerful powder. Later, powder for very large ordnance was made from charcoal that was deliberately “overburned” to reduce the initial burning rate and, hence, the stress on the gun.

Beginning in the mid-19th century, the use of extremely large guns for naval warfare and coastal defense pressed existing materials and methods of cannon construction to the limit. This led to the development of methods for measuring pressures within the gun, which involved cylindrical punches mounted in holes drilled at right angles through the barrel. The pressure of the propellant gases forced the punches outward against soft copper plates, and the maximum pressure was then determined by calculating the amount of pressure needed to create an indentation of equal depth in the copper. The ability to measure pressures within a gun led to the design of cannon made thickest where internal pressures were greatest—that is, near the breech. The resultant “soda bottle” cannon of the mid- to late 19th century, which had fat breeches curving down to short, slim muzzles, bore a strange resemblance to the very earliest European gun of which a depiction survives, that of the Walter de Millimete manuscript of 1327.

The earliest known gunpowder weapons vaguely resembled an old-fashioned soda bottle or a deep-throated mortar and pestle. The earliest such weapon, depicted in the English de Millimete manuscript, was some three feet long with a bore diameter of about two inches (five centimetres). The projectile resembled an arrow with a wrapping around the shaft, probably of leather, to provide a gas seal within the bore. Firing was apparently accomplished by applying a red-hot wire to a touchhole drilled through the top of the thickest part of the breech. The gun was laid horizontally on a trestle table without provision for adjusting elevation or absorbing recoil—a tribute to its modest power, which would have been only marginally greater than that of a large crossbow.

The breakthrough that led to the emergence of true cannon derived from three basic perceptions. The first was that gunpowder’s propellant force could be used most effectively by confining it within a tubular barrel. This stemmed from an awareness that gunpowder’s explosive energy did not act instantaneously upon the projectile but had to develop its force across time and space. The second perception was that methods of construction derived from cooperage could be used to construct tubular wrought-iron gun barrels. The third perception was that a spherical ball was the optimal projectile. The result was modern artillery.

The earliest guns were probably cast from brass or bronze. Bell-founding techniques would have sufficed to produce the desired shapes, but alloys of copper, tin, and zinc were expensive and, at first, not well adapted to the containment of high-temperature, high-velocity gases. Wrought iron solved both of these problems. Construction involved forming a number of longitudinal staves into a tube by beating them around a form called a mandrel and welding them together. (Alternatively, a single sheet of iron could be wrapped around the mandrel and then welded closed; this was particularly suitable for smaller pieces.) The tube was then reinforced with a number of rings or sleeves (in effect, hoops). These were forged with an inside diameter about the same as the outside of the tube, raised to red or white heat, and slid into place over the cooled tube, where they were held firmly in place by thermal contraction. The sleeves or rings were butted against one another and the gaps between them sealed by a second layer of hoops. Forging a strong, gastight breech presented a particular problem that was usually solved by welding a tapered breech plug between the staves.

Hoop-and-stave construction permitted the fabrication of guns far larger than had been made previously. By the last quarter of the 14th century, wrought-iron siege bombards were firing stone cannonballs of 450 pounds (200 kilograms) and more. These weapons were feasible only with projectiles of stone. Cast iron has more than two and a half times the density of marble or granite, and gunners quickly learned that a cast-iron cannonball with a charge of good corned powder behind it was unsafe in any gun large enough for serious siege work.

Partly because of the difficulties of making a long, continuous barrel, and partly because of the relative ease of loading a powder charge into a short breechblock, gunsmiths soon learned to make cannon in which the barrel and powder chamber were separate. Since the charge and projectile were loaded into the rear of the barrel, these were called breechloaders. The breechblock was mated to the barrel by means of a recessed lip at the chamber mouth. Before firing, it was dropped into the stock and forced forward against the barrel by hammering a wedge into place behind it; after the weapon was fired, the wedge was knocked out and the block was removed for reloading. This scheme had significant advantages, particularly in the smaller classes of naval swivel guns and fortress wallpieces, where the use of multiple breechblocks permitted a high rate of fire. Small breechloaders continued to be used in these ways well into the 17th century.

The essential deficiency of early breechloaders was the imperfect gas seal between breechblock and barrel, a problem that was not solved until the advent of the brass cartridge late in the 19th century. Hand-forging techniques could not produce a truly gastight seal, and combustion gases escaping through the inevitable crevices eroded the metal, causing safety problems. Wrought-iron cannon must have required constant maintenance and care, particularly in a saltwater environment.

Wrought-iron breechloaders were the first cannon to be produced in significant numbers. Their tactical viability was closely linked to the economics of cannonballs of cut stone, which, modern preconceptions to the contrary, were superior to cast-iron projectiles in many respects. Muzzle velocities of black-powder weapons were low, and smoothbore cannon were inherently inaccurate, so that denser projectiles of iron had no advantage in effective range. Cannon designed to fire a stone projectile were considerably lighter than those designed to fire an iron ball of the same weight; as a result, stone-throwing cannon were for many years cheaper. Also, because stone cannonballs were larger than iron ones of the same weight, they left larger holes after penetrating the target. The principal deficiency of stone-throwing cannon was the enormous amount of skilled labour required to cut a sphere of stone accurately to a predetermined diameter. The acceleration of the wage–price spiral in the 15th and 16th centuries made stone-throwing cannon obsolete in Europe.

The advantages of cast bronze for constructing large and irregularly shaped objects of a single piece were well understood from sculpture and bell founding, but a number of problems had to be overcome before the material’s plasticity could be applied to ordnance. Most important, alloys had to be developed that were strong enough to withstand the shock and internal pressures of firing without being too brittle. This was not simply a matter of finding the optimal proportions of copper and tin; bronze alloys used in cannon founding were prone to internal cavities and “sponginess,” and foundry practices had to be developed to overcome the inherent deficiencies of the metal. The essential technical problems were solved by the first decades of the 15th century, and, by the 1420s and ’30s, European cannon founders were casting bronze pieces that rivaled the largest of the wrought-iron bombards in size.

Developments in foundry practice were accompanied by improvements in weapon design. Most notable was the practice of casting cylindrical mounting lugs, called trunnions, integral with the barrel. Set just forward of the centre of gravity, trunnions provided the principal point for attaching the barrel to the carriage and a pivot for adjusting the vertical angle of the gun. This permitted the barrel to be adjusted in elevation by sliding a wedge, or quoin, beneath the breech. At first, trunnions were supplemented by lifting lugs cast atop the barrel at the centre of gravity; by the 16th century most European founders were casting these lugs in the shape of leaping dolphins, and a similarly shaped fixture was often cast on the breech of the gun.

Toward the end of the 15th century, French founders combined these features with efficient gun carriages for land use. French carriage design involved suspending the barrel from its trunnions between a pair of heavy wooden side pieces; an axle and two large wheels were then mounted forward of the trunnions, and the rear of the side pieces descended to the ground to serve as a trail. The trail was left on the ground during firing and absorbed the recoil of the gun, partly through sliding friction and partly by digging into the ground. Most important, the gun could be transported without dismounting the barrel by lifting the trail onto the limber, a two-wheeled mount that served as a pivoting front axle and point of attachment for the team of horses. This improved carriage, though heavy in its proportions, would have been familiar to a gunner of Napoleonic times. Sometime before the middle of the 16th century, English smiths developed a highly compact four-wheeled truck carriage for mounting trunnion-equipped shipboard ordnance, resulting in cannon that would have been familiar to a naval gunner of Horatio Nelson’s day.

By the early 1500s, cannon founders throughout Europe had learned to manufacture good ordnance of cast bronze. Cannon were cast in molds of clay, suspended vertically in a pit. Normally, they were cast breech down; this placed the molten metal at the breech under pressure, resulting in a denser and stronger alloy around the chamber, the most critical point. Subsequent changes in foundry practice were incremental and took effect gradually. As founders established mastery over bronze, cannon became shorter and lighter. In about 1750, advances in boring machines and cutting tools made it possible for advanced foundries to cast barrels as solid blanks and then bore them out. Until then cannon were cast hollow—that is, the bore was cast around a core suspended in the mold. Ensuring that the bore was precisely centred was a particularly critical part of the casting process, and small wrought-iron fixtures called chaplets were used to hold the core precisely in place. These were cast into the bronze and remained a part of the gun. Boring produced more accurate weapons and improved the quality of the bronze, since impurities in the molten metal, which gravitate toward the centre of the mold during solidification, were removed by the boring. But, while these changes were important operationally, they represented only marginal improvements to the same basic technology. A first-class bronze cannon of 1500 differed hardly at all in essential technology and ballistic performance from a cannon of 1850 designed to shoot a ball of the same weight. The modern gun would have been shorter and lighter, and it would have been mounted on a more efficient carriage, but it would have fired its ball no farther and no more accurately.

In 1543 an English parson, working on a royal commission from Henry VIII, perfected a method for casting reasonably safe, operationally efficient cannon of iron. The nature of the breakthrough in production technology is unclear, but it probably involved larger furnaces and a more efficient organization of resources. Cast-iron cannon were significantly heavier and bulkier than bronze guns firing the same weight of ball. Unlike bronze cannon, they were prone to internal corrosion. Moreover, when they failed, they did not tear and rupture like bronze guns but burst into fragments like a bomb. They possessed, however, the overwhelming advantage of costing only about one-third as much. This gave the English, who alone mastered the process until well into the 17th century, a significant commercial advantage by enabling them to arm large numbers of ships. The Mediterranean nations were unable to cast significant quantities of iron artillery until well into the 19th century.

cannonIllustration of cannons from the first edition of the Encyclopædia Britannica, vol. 2, plate XCVIII.Encyclopædia Britannica, Inc.

Early use of artillery

Terminology and classification

Early gunpowder artillery was known by a bewildering variety of names. (The word cannon became dominant only gradually, and the modern use of the term to describe a gun large enough to fire an explosive shell did not emerge until the 20th century.) The earliest efficient wrought-iron cannon were called bombards or lombards, a term that continued in use well into the 16th century. The term basilisk, the name of a mythical dragonlike beast of withering gaze and flaming breath, was applied to early “long” cannon capable of firing cast-iron projectiles, but, early cannon terminology being anything but consistent, any particularly large and powerful cannon might be called a basilisk.

Founders had early adopted the practice of classifying cannon by the weight of the ball, so that, for example, a 12-pounder fired a 12-pound cannonball. By the 16th century, gunners had adopted the custom of describing the length of a cannon’s bore in calibres, that is, in multiples of the bore diameter. These became basic tools of classification and remained so into the modern era with certain categories of ordnance such as large naval guns. Also by the 16th century, European usage had divided ordnance into three categories according to bore length and the type of projectile fired. The first category was the culverins, “long” guns with bores on the order of 30 calibres or more. The second was the cannons, or cannon-of-battery, named for their primary function of battering down fortress walls; these typically had barrels of 20 to 25 calibres. The third category of ordnance was the pedreros, stone-throwing guns with barrels of as little as eight to 10 calibres that were used in siege and naval warfare.

Mortars were a separate type of ordnance. With very wide bores of even fewer calibres than those of the pedreros, they were used in siege warfare for lobbing balls at a very high trajectory (over 45°). Mortars owed their name to the powder chamber of reduced diameter that was recessed into the breech; this made them similar in appearance to the mortars used to pulverize grain and chemicals by hand. Unlike the longer cannon, mortars were cast with trunnions at the breech and were elevated by placing wedges beneath the muzzle.

Special-purpose shot

Both culverins and cannon-of-battery generally fired cast-iron balls. When fired against masonry walls, heavy iron balls tended to pulverize stone and brick. Large stone cannonballs, on the other hand, were valued for the shock of their impact, which could bring down large pieces of wall. Undercutting the bottom of a wall with iron cannonballs, then using the heavy impact of large stone shot to bring it down, was a standard tactic of siege warfare. (Ottoman gunners were particularly noted for this approach.)

In the 15th century exploding shot was developed by filling hollow cast-iron balls with gunpowder and fitting a fuze that had to be lit just before firing. These ancestors of the modern exploding shell were extremely dangerous to handle, as they were known to explode prematurely or, with equally catastrophic results, jam in the gun barrel. For this reason they were used only in the short-bored mortars.

For incendiary purposes, iron balls were heated red-hot in a fire before loading. (In that case, moist clay was sometimes packed atop the wadding that separated the ball from the powder charge.) Other projectiles developed for special purposes included the carcass, canister, grapeshot, chain shot, and bar shot. The carcass was a thin-walled shell containing incendiary materials. Rounds of canister and grapeshot consisted of numerous small missiles, usually iron or lead balls, held together in various ways for simultaneous loading into the gun but designed to separate upon leaving the muzzle. Because they dispersed widely upon leaving the gun, the projectiles were especially effective at short range against massed troops. Bar shot and chain shot consisted of two heavy projectiles joined by a bar or a chain. Whirling in their trajectories, they were especially effective at sea in cutting the spars and rigging of sailing vessels.

Gunnery

During most of the black-powder era, with smoothbore cannon firing spherical projectiles, artillery fire was never precisely accurate at long ranges. (Aiming and firing were particularly difficult in naval gunnery, since the gunner had to predict the roll of the ship in order to hit the target.) Gunners aimed by sighting along the top of the barrel, or “by the line of metals,” then stepped away before firing to avoid the recoil. The basic relationship between range and elevation being understood, some accuracy was introduced through the use of the gunner’s quadrant, in which the angle of elevation of a gun barrel was measured by inserting one leg of the quadrant into the barrel and reading the angle marked on the scale by a vertically hanging plumb line. Nevertheless, the inherent inaccuracy of smoothbore artillery meant that most shooting was done at short ranges of 1,000 yards or less; at these ranges, estimating elevation by rule of thumb was sufficient. For attacking fortress walls, early modern gunners preferred a range of 60 to 80 yards; a range of 100 to 150 yards was acceptable, but 300 yards or more was considered excessive.

Small arms did not exist as a distinct class of gunpowder weapon until the middle of the 15th century. Until then, hand cannon differed from their larger relatives only in size. They looked much the same, consisting of a barrel fastened to a simple wooden stock that was braced beneath the gunner’s arm. A second person was required to fire the weapon. About the middle of the 15th century, a series of connected developments established small arms as an important and distinct category of weaponry. The first of these was the development of slow match—or match, as it was commonly called. This was cord or twine soaked in a solution of potassium nitrate and dried. When lit, match smoldered at the end in a slow, controlled manner. Slow match found immediate acceptance among artillerists and remained a standard part of the gunner’s kit for the next four centuries.

Small arms appeared during the period 1460–80 with the development of mechanisms that applied match to hand-portable weapons. German gunsmiths apparently led the way. The first step was a simple S-shaped “trigger,” called a serpentine, fastened to the side of a hand cannon’s stock. The serpentine was pivoted in the middle and had a set of adjustable jaws, or dogs, on the upper end that held the smoldering end of a length of match. Pulling up on the bottom of the serpentine brought the tip of the match down into contact with powder in the flashpan, a small, saucer-shaped depression surrounding the touchhole atop the barrel. This arrangement made it possible for one gunner to aim and fire, and it was quickly improved on. The first and most basic change was the migration of the touchhole to the right side of the barrel, where it was served by a flashpan equipped with a hinged or pivoting cover that protected the priming powder from wind, rain, and rough handling. The serpentine was replaced by a mechanism, enclosed within the gunstock, that consisted of a trigger, an arm holding the match with its adjustable jaws at the end, a sear connecting trigger and arm, and a mechanical linkage opening the flashpan cover as the match descended. These constituted the matchlock, and they made possible modern small arms.

One final refinement was a spring that drove the arm holding the match downward into the pan when released by the sear. This mechanism, called the snap matchlock, was the forerunner of the flintlock. The fabrication of these devices fell to locksmiths, the only sizable body of craftsmen accustomed to constructing metal mechanisms with the necessary ruggedness and precision. They gave to the firing mechanism the enduring name lock.

The development of mechanical locks was accompanied by the evolution of gunstocks with proper grips and an enlarged butt to transmit the recoil to the user’s body. The result was the matchlock harquebus, the dominant military small arm of the 15th century and the direct ancestor of the modern musket. The harquebus was at first butted to the breastbone, but, as the power of firearms increased, the advantages of absorbing the recoil on the shoulder came to be appreciated. The matchlock harquebus changed very little in its essentials until it was replaced by the flintlock musket in the final years of the 17th century.

The principal difficulty with the matchlock mechanism was the need to keep a length of match constantly smoldering. German gunsmiths addressed themselves to this problem early in the 16th century. The result was the wheel lock mechanism, consisting of a serrated wheel rotated by a spring and a spring-loaded set of jaws that held a piece of iron pyrites against the wheel. Pulling the trigger caused the wheel to rotate, directing a shower of sparks into the flashpan. The wheel lock firearm could be carried in a holster and kept ready to fire indefinitely, but, being delicate and expensive, it did not spread beyond cavalry elites and had a limited impact on warfare as a whole.

Flintlock firing mechanisms were known by the middle of the 16th century, about a hundred years before they made their appearance in quantity in infantry muskets. A flintlock was similar to a wheel lock except that ignition came from a blow of flint against steel, with the sparks directed into the priming powder in the pan. This lock was an adaptation of the tinderbox used for starting fires.

In the several different types of flintlocks that were produced, the flint was always held in a small vise, called a cock, which described an arc around its pivot to strike the steel (generally called the frizzen) a glancing blow. A spring inside the lock was connected through a tumbler to the cock. The sear, a small piece of metal attached to the trigger, either engaged the tumbler inside the lock or protruded through the lock plate to make direct contact with the cock.

Flintlocks were not as surefire as either the matchlock or the wheel lock, but they were cheaper than the latter, contained fewer delicate parts, and were not as difficult to repair in primitive surroundings. In common with the wheel locks they had the priceless advantage of being ready to fire immediately. A flintlock small arm was slightly faster to load than a matchlock, if the flint itself did not require adjustment.

Before gunpowder artillery, a well-maintained stone castle, secured against escalade by high curtain walls and flanking towers, provided almost unbreachable security against attack. Artillery at first did little to change this. Large wrought-iron cannon capable of throwing wall-smashing balls of cut stone appeared toward the end of the 14th century, but they were neither efficient nor mobile. Indeed, the size and unwieldiness of early firearms and cannon suited them more for fortress arsenals than for the field, and adjustments to gunpowder by fortification engineers quickly tilted the balance of siege operations toward the defense. Gunports were cut low in walls for covering ditches with raking fire, reinforced platforms and towers were built to withstand the recoil shock of defensive cannon, and the special firing embrasures for crossbows were modified into gunports for hand cannon, with sophisticated vents to carry away the smoke. The name of the first truly effective small arm, the Hackenbüsche, or hackbut, is indicative: the weapon took its name, literally “hook gun,” from a projection welded beneath the forward barrel that was hooked over the edge of a parapet in order to absorb the piece’s recoil.

From medieval to modern

The inviolability of the medieval curtain wall came to an end in the 15th century, with the development of effective cast-bronze siege cannon. Many of the basic technical developments that led to the perfection of heavy bronze ordnance were pioneered by German founders. Frederick I, elector of Brandenburg from 1417 to 1425, used cannon systematically to defeat the castles of his rivals one by one in perhaps the earliest politically decisive application of gunpowder technology. The French and Ottomans were the first to bring siege artillery to bear in a decisive manner outside their own immediate regions. Charles VII of France (reigned 1422–61) used siege artillery to reduce English forts in the last stages of the Hundred Years’ War. When his grandson Charles VIII invaded Italy in 1494, the impact of technically superior French artillery was immediate and dramatic; the French breached in eight hours the key frontier fortress of Monte San Giovanni, which had previously withstood a siege of seven years.

The impact of Ottoman siege artillery was equally dramatic. Sultan Mehmed II breached the walls of Constantinople in 1453 by means of large bombards, bringing the Byzantine Empire to an end and laying the foundations of Ottoman power. The Turks retained their superiority in siegecraft for another generation, leveling the major Venetian fortifications in southern Greece in 1499–1500 and marching unhindered through the Balkans before being repulsed before Vienna in 1529.

The shock of the sudden vulnerability of medieval curtain walls to French, Ottoman, and, to a lesser extent, German siege cannon quickly gave way to attempts by military engineers to redress the balance. At first, these consisted of the obvious and expensive expedients of counter-battery fire. By the 1470s, towers were being cut down to the height of the adjacent wall, and firing platforms of packed earth were built behind walls and in the lower stories of towers. Italian fortress architects experimented with specially designed artillery towers with low-set gunports sited to sweep the fortress ditch with fire; some were even sited to cover adjacent sections of wall with flanking fire. However, most of these fortresses still had high, vertical walls and were therefore vulnerable to battery.

A definitive break with the medieval past was marked by two Italian sieges. The first of these was the defense of Pisa in 1500 against a combined Florentine and French army. Finding their wall crumbling to French cannon fire, the Pisans in desperation constructed an earthen rampart behind the threatened sector. To their surprise and relief, they discovered not only that the sloping earthen rampart could be defended against escalade but that it was far more resistant to cannon shot than the vertical stone wall that it supplanted. The second siege was that of Padua in 1509. Entrusted with the defense of this Venetian city, a monk-engineer named Fra Giocondo cut down the city’s medieval wall. He then surrounded the city with a broad ditch that could be swept by flanking fire from gunports set low in projections extending into the ditch. Finding that their cannon fire made little impression on these low ramparts, the French and allied besiegers made several bloody and fruitless assaults and then withdrew.

The sunken profile

While Pisa demonstrated the strength of earthen ramparts, Padua showed the power of a sunken profile supported by flanking fire in the ditch. With these two cities pointing the way, basic changes were undertaken in fortress design. Fortress walls, still essential for protection against escalade, were dropped into the ground behind a ditch and protected from battery by gradually sloping earthen ramparts beyond. A further refinement was the sloping of the glacis, or forward face of the ramparts, in such a manner that it could be swept by cannon and harquebus fire from the parapet behind the ditch. As a practical matter the scarp, or main fortress wall, now protected from artillery fire by the glacis, was faced with brick or stone for ease of maintenance; the facing wall on the forward side of the ditch, called the counterscarp, was similarly faced. Next, a level, sunken space behind the glacis, the covered way, was provided so that defenders could assemble for a sortie under cover and out of sight of the attackers. This, and the provision of firing embrasures for cannon in the parapet wall, completed the basics of the new fortress profile.

European fortressProfile of the European fortress wall from the 16th century.Encyclopædia Britannica, Inc.

Refinements of the basic sunken design included a palisade of sharpened wooden stakes either in the ditch or immediately behind the glacis and a sunken, level path behind the parapet for ammunition carts, artillery reinforcements, and relief troops. As attacking and defending batteries became larger, fortress designers placed greater emphasis on outworks intended to push the besieging batteries farther back and out of range.

The profile of the outworks was designed according to the same basic principles applied to the fortress. Well established by 1520, these principles remained essentially unchanged until rifled artillery transformed positional warfare in the mid-19th century.

The bastioned trace

The sunken profile was only half the story of early modern fortress design; the other half was the trace, the outline of the fortress as viewed from above. The new science of trace design was based, in its early stages, on the bastion, a projection from the main fortress wall from which defending fire could sweep the face of adjacent bastions and the wall between. Actually, bastions had been introduced before engineers were fully aware of the power of artillery, so that some early 16th-century Italian fortifications combined sophisticated bastioned traces with outmoded high walls, a shallow ditch, and little or no protective glacis. After early experimentation with rounded contours, which were believed to be stronger, designers came to appreciate the advantages of bastions with polygonal shapes, which eliminated the dead space at the foot of circular towers and provided uninterrupted fields of view and fire. Another benefit of the polygonal bastion’s long, straight sections of wall was that larger defensive batteries could be mounted along the parapets.

The relatively simple traces of the early Italian bastioned fortresses proved vulnerable to the ever larger armies and ever more powerful siege trains of the 16th century. In response, outworks were developed, such as ravelins (detached outworks in front of the bastions) and demilunes (semidetached outworks in the ditch between bastions), to shield the main fortress walls from direct battery. The increasing scale of warfare and the greater resources available to the besieger accelerated this development, and systems of outworks grew more and more elaborate and sprawling as a means of slowing the attacker’s progress and making it more costly.

By the late 17th century, fortress profiles and traces were closely integrated with one another and with the ground on which they stood. The sophistication of their designs is frequently linked with the name of the French military engineer Sébastien Le Prestre de Vauban.

Duration of early modern fortification

With various refinements, the early modern fortress, based on a combination of the sunken profile and bastioned trace, remained the basic form of permanent fortification until the American Civil War, which saw the first extensive use of heavy rifled cannon made of high-quality cast iron. These guns not only had several times the effective range and accuracy of their predecessors, but they were also capable of firing explosive shells. They did to the early modern fortress what cast-bronze cannon had done to the medieval curtain wall. In 1862 the reduction by rifled Union artillery of Fort Pulaski, a supposedly impregnable Confederate fortification defending Savannah, Georgia, marked the beginning of a new chapter in the design of permanent fortifications.